Portable, cellular phones are increasingly utilized to permit a user to communicate telephonically over a wireless system at virtually any location. The portable telephone transmits a low wattage, radio frequency signal to a receiving station whereat connections are provided with conventional telephone systems. Numerous receiving stations are spaced apart at fixed locations in an area to receive the signals transmitted by the portable telephone as the portable telephone is relocated throughout the area.
Telephones utilizing two housing elements connected with some type of hinging mechanism, are common in wireline telephone sets and landline wireless extension phones and have become more common in portable cellular radiotelephones. This folding arrangement allows for the telephone to be more compact when the two housings are folded upon themselves.
Some radiotelephones which utilize this type of design have most of the electronics within the larger of the two housings. The smaller housing, which will be called the flip element hereinafter, normally contains the microphone and the ringing element. For good acoustical performance, the flip element must be held in an optimum position relative to the body of the radiotelephone. In doing so, the microphone is positioned a desired distance from the user's mouth.
Other radiotelephones which utilize this type of design have all the electronics within the larger of the two housings. The flip element contains no electronics. A flip element of this sort may have the capability of producing an on-hook condition when the flip element is in the "closed" position and an off-hook condition when the flip element is rotated to its "opened" position. A radiotelephone which employs the position of the flip element for control purposes was described in U.S. Pat. No. 4,845,772. When the flip element is in its "closed" position the radiotelephone is in a standby state ready to receive an incoming call. The flip element covers at least a portion of the keypad on the body of the radiotelephone thereby shielding the keys to avoid accidental key depression or contamination of the keys with foreign material. When the flip element is in the "opened" position, some background noise is shielded from the microphone by the flip element.
A variety of techniques have been used to position the flip element in the closed and open position. A radiotelephone which holds the flip element in the closed and open position using an enclosed cam element which follows recesses in one shaft securing the hinge elements was described in U.S. Pat. No. 4,897,873. A cellular telephone named "Pocket Commander" (.TM.) manufactured by Fujitsu model no. F80P-171 utilizes a partially cylindrical hinge shaft having two essentially planar surfaces. The the plane of the each planar surface intersects to form an acute angle. A U-shaped wire spring, held in a fixed position, applies pressure to one planar surface of the rectangular portion of the hinge shaft to hold the flip element in its closed position. As the flip element is rotated, the wire spring expands around the cylindrical surface portion of the hinge shaft until the wire spring applies pressure to the other planar surface of the rectangular hinge portion of the hinge shaft to hold the flip element is then held in its open position. A cordless radiotelephone manufactured by Panasonic model no. KX-T3000H utilizes a helical spring having each end extended beyond the helix forming a predetermined obtuse angle. One end of the helical spring is attached to the flip element. The other end of the helical spring is attached to the body of the radiotelephone. In its closed position the flip element is latched to the body of the radiotelephone. When the latch is released the flip element springs away from the body of the radiotelephone to its open position determined by the obtuse angle formed by the ends of the helical spring.
Such assemblies which predetermine the position of the flip element, however, require a multiple-step process in order to a fix the hinge assembly to the housing of the radiotelephone. Such a process is time consuming and additionally, is susceptible to assembly error and/or subsequent failure during use of the assembly.
Furthermore, increased miniaturization of radiotelephones allow the radio telephones to be packaged in housing of even smaller dimensions. The hinge assemblies described herein above are of dimensions which limits further decrease in the housing size of the radiotelephone.
Therefore, a new hinge assembly design is required which is of simpler construction as well as of smaller dimensions.